1:
2:
3:
4:
5:

\left(
\begin{matrix} a&a&a\\ b&b&b\\ c&c&c \end{matrix} 
\left| 
\begin{matrix}1&0&0\\ 0&1&0\\ 0&0&1 \end{matrix}
\right) \right|

1:
2:
3:
4:
5:

\left(
\begin{matrix} a&a&a\\ b&b&b\\ c&c&c \end{matrix} 
\left| 
\begin{matrix}1&0&0\\ 0&1&0\\ 0&0&1 \end{matrix}
\right) \right.

1:
2:
3:
4:
5:

\left( \begin{array}{ccc|ccc}
a & a & a & 1 & 0 & 0 \\ 
b & b & b & 0 & 1 & 0 \\
c & c & c & 0 & 0 & 1
\end{array}\right)